feat(cname-prefix): add isPrefixedCdnBase helper

[nd0ut]

Description

Checklist

• Tests (if applicable)
• Documentation (if applicable)
• Changelog stub (or use conventional commit messages)

[Copilot]

Pull Request Overview

Adds a new helper to determine whether a given CDN base URL includes a specified prefix subdomain, and exposes it across sync, async, and main package entries.

• Implements isPrefixedCdnBase in common/
• Exports the helper in async/index.ts, sync/index.ts, and package root index.ts
• Provides unit tests covering typical and invalid URL cases

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/cname-prefix/src/common/isPrefixedCdnBase.ts	Added isPrefixedCdnBase helper implementation
packages/cname-prefix/src/common/isPrefixedCdnBase.test.ts	Introduced unit tests for the new helper
packages/cname-prefix/src/async/index.ts	Re-exported helper in the async entry point
packages/cname-prefix/src/sync/index.ts	Re-exported helper in the sync entry point
packages/cname-prefix/src/index.ts	Exposed helper in main package entry

Comments suppressed due to low confidence (3)

packages/cname-prefix/src/common/isPrefixedCdnBase.ts:1

• [nitpick] Consider adding a JSDoc comment above this function to explain its purpose, parameters, return value, and edge-case behavior for better readability and maintainability.

export const isPrefixedCdnBase = (cdnBase: string, prefixCdnBase: string) => {

packages/cname-prefix/src/common/isPrefixedCdnBase.test.ts:34

• Add a test for multi-level subdomains (e.g. 'https://a.b.ucarecd.net', 'https://ucarecd.net') to verify the helper handles deeper prefix chains as intended.

})

packages/cname-prefix/src/index.ts:3

• [nitpick] Remember to update the package README and CHANGELOG to document the new isPrefixedCdnBase helper as part of the public API.

export { isPrefixedCdnBase } from './common/isPrefixedCdnBase'

[Copilot]

The helper currently only handles exactly three hostname parts, which will fail for multi-level subdomains. Consider using cdnBaseUrl.hostname.endsWith(.${prefixCdnBaseUrl.hostname}) to simplify the logic and support arbitrary subdomain depths.

Suggested change

	const cdnBaseHostnameParts = cdnBaseHostname.split('.')
	if (cdnBaseHostnameParts.length !== 3) {
	return false
	}
	const [, sld, tld] = cdnBaseHostnameParts
	const cdnBaseHostnameWithoutPrefix = `${sld}.${tld}`
	return prefixCdnBaseUrl.hostname === cdnBaseHostnameWithoutPrefix
	return cdnBaseHostname.endsWith(`.${prefixCdnBaseUrl.hostname}`)